REVUE DE MICROPALEONTOLOGIE最新文献

A 3 m thick carbonate sequence from northern Chios Island is assigned here to the latest Capitanian/earliest Wuchiapingian transitional interval. It is characterized by abundant gymnocodiacean algae, associated with some miliolate, nankinellin and nodosariate foraminifers. These strata display bioaccumulated perireefal microfacies with richthofeniid brachiopods and inozoa calcisponges. They are biostratigraphically characterized by a foraminifera assemblage composed of Reichelina cf. simplex, Dunbarula? sp., Altineria alpinotaurica together with the genera Labioglobivalvulina, Frondina and Robuloides. Other perireefal microfacies show abundant fragments of a new tubiphytid species, Tubiphytella guevenci Vachard nov. gen. nov. sp. Based on this study, the paleogeographical distribution of Altineria alpinotaurica now includes Chios, in addition to the Taurus and the NW and central Iran, whereas primitive forms of the genus are also known in Tunisia and Armenia. This paleobiogeographic distribution would suggest that all these regions still belonged to the Perigondwana margin in the early Wuchiapingian times. Consequently, it is likely that the opening of the Neotethys ocean did not begin prior to the late Wuchiapingian-early Changshingian transitional interval.

We describe paper models which represent the cortical shell structures of radiolarian genus Pantanellium using the unit origami method: the construction of a polyhedral frame using origami units. Each unit corresponds to the edge of a polyhedron. The models are constructed based on planar graphs representing the cortical shell structures of real specimens. The resulting models reproduce the cortical shell structures appropriately. This means that the origami model is useful for both naked-eye practical observation of shell structures and group educational/art activities.

Introduction of new, more specialized, non-destructive techniques into palaeoenvironmental and palaeoclimatic research, has proven to be of a great asset, over the last decades. Geoarchives like sediment cores can thus be studied with much higher resolution, faster and with less effort, providing significantly more information about sediment composition, grain size and structure. In this study, we applied X-ray fluorescence (XRF) and computed tomography (CT) analysis on two different sediment cores, retrieved from a typical lagoonal environment and a marsh field in western Peloponnese, Greece. XRF scanning was used with a step of 0.5 cm in order to obtain a detailed elemental profile of the core, whereas CT scan was performed with a resolution of 0.3 mm. Concerning elemental compound and X-ray absorption, distinct correlation between HU and terrigenous elements was observed. Furthermore, through 3D reconstruction of the cores sections, we explored possible methods for fauna/sediment ratio, as well as microstructural characteristics. The combined appliance of those two techniques on the two sediment cores that were studied seems to provide robust results concerning sedimentological facies, biofacies and sediment structure.

This study discusses three species of Stylotrochus recently observed in small numbers in six cores from the southern Indian Ocean and seven in the Bellingshausen Basin. It describes their geographical and chronological distributions and relates them to the reports of previous researchers. It also seeks to erect two new species of Stylotrochus, one of which is designed to replace Spongodiscus biconcavus, nomen dubium.

A new orbitolinid is described as Orbitolinopsis cenomaniensis n. sp. from the middle-?late Cenomanian of the Sarvak Formation, Zagros Zone, SW Iran. It is characterized by a high-conical test, a simple embryo consisting of proloculus and deuteroconch in subapical position, a rather narrow marginal zone and a prominent central zone with cupules that can present a jagged outline. The regular occurrence of one short rafter is considered a species characteristic of the species, one case that is also encountered in other dictyoconid taxa (e.g., Montseciella, Paracoskinolina, Simplorbitolina, Valserina). Single sporadic rafters have been reported from the early Albian Orbitolinopsis ajoensis Schlagintweit et al. demonstrating a distinct trend towards an increasing in morphological complexity. The Iranian find represents the first record of Orbitolinopsis from the Cenomanian. Like several other taxa of larger benthic foraminifera (agglutinating and porcelaneous), O. cenomaniensis is here considered an endemic taxon for the Arabian Plate.

A new radiolarian assemblage was recovered from upper Ladinian–lower Carnian strata of the southeastern part of Omolon Massif. The assemblage has several taxa in common with the upper Ladinian of the western part of the Omolon Massif and the lower Carnian of Kotel’nyi Island (New Siberian Islands, Arctic) and displays clear boreal features: low taxonomic and morphological diversity, abundance of taxa known from high-latitude regions and rare presence of taxa known from low-latitude areas. Two new species are described: Praenanina? hirsuta nov. sp. and Hindeosphaera venusta nov. sp.

Well-preserved Late Cretaceous (early Cenomanian) radiolarians were recovered from two sections in Crimea: Bodrak River and Sel’-Bukhra Mountain sections. Abundant and diverse representatives of order Spumellaria were recognized and studied. Four new radiolarian species: Becus naidini nov. sp., B. tauricus nov. sp., Praeconocaryomma? bodrakensis nov. sp., and Savaryella? nikishini nov. sp. were described. Moreover, stratigraphical ranges of species Archaeospongoprunum sphaericum Bragina, Crucella lata (Lipman), Patellula cognata O’Dogherty, P. verteroensis (Pessagno), Spongodiscus quasipersenex Bragina were exactly defined (their lower limits are expanded to the lower Cenomanian). The upper limit of stratigraphic range of "Cenodiscus" alievi Pessagno is expanded to the lower Cenomanian. Our results suggest that two rare taxa "Cenodiscus" alievi Pessagno (California Coast Ranges) and Spongodiscus quasipersenex Bragina (West Sakhalin Mountains) are reported for the first time in the Tethyan regions.